1. Field
The present disclosure relates generally to power management integrated circuits, and more particularly, to current derating with integrated temperature sensing.
2. Background
Power management integrated circuits (PMIC) for mobile devices have grown in importance as the features and functions of mobile devices have increased. PMICs integrate various modules such as voltage regulators, battery chargers, drivers, audio amplifiers, and user interfaces, among other features. Many of these modules dissipate considerable power and are frequently turned on at the same time, causing elevated chip temperatures. Elevated chip temperatures may cause thermal shutdown and other problems if not properly managed. Current PMICs incorporate a temperature alarm module that monitors the PMIC temperature and sends out interrupts as needed, depending on the temperature and threshold.
Power dissipation prediction and thermal management is made more complex by the concurrent operation of multiple modules, each of which generates an additional thermal load. A practical method for addressing the thermal loading problem is to limit, or derate, power consumption of modules such as the Flash LED and audio amplifier when those modules are operating in an elevated thermal condition, or generating more heat that must be dissipated. Existing PMIC temperature alarms output a voltage measurement, which must be converted to current before being used in a current derating operation. This current derating operation may require a large look-up table in order to provide a smooth derating of the current. In addition, the temperature alarm sensor may be physically located far away from the LED module and this distance may also cause error in the derating temperature threshold for the Flash Module.
There is a need in the art for a method and apparatus to implement thermal sensing and management in modules such as the Flash LED module and implement current derating with integrated temperature management, while avoiding errors in latency and current derating. In addition, there is a need in the art for a method and apparatus that provides automatic and smooth temperature derating, flexible derating control, compact design, and low cost.